The present invention generally relates to fuel caps for use with fuel tanks and, more particularly, is concerned with a fuel cap having an anti-splash attachment.
Small gasoline engine powered machines, such as lawn mowers, garden tillers, snowblowers, electrical generators and the like, have fuel tanks attached to them. For closing the fuel tank, a fuel cap is applied to the open end of a filler neck connected to and extending from the fuel tank. The fuel cap is commonly constructed to prevent escape of liquid fuel from the fuel tank while, at the same time, permitting venting of the tank to the atmosphere.
One prior art fuel cap, so constructed, provides sufficient clearance at the connection between its internal threads and the external threads on the end of the filler neck to define a path therethrough for venting the fuel tank. To impede migration of liquid fuel to the venting path between the threaded connection of the fuel cap to the filler neck, the fuel cap employs an inverted dome-shaped circular gasket, a foam element disposed in a cavity above the gasket leading to the threaded connection, and a conical splash-back baffle disposed below and connected to the gasket. The foam element normally allows passage of vapors and impedes passage of liquid fuel. The foam which has been used in the past is an open-cell polyurethane that expands when it is contacted by fuel.
The construction of this fuel cap is adequate under some conditions to allow venting of the fuel tank to the external atmosphere along the above-described path and to prevent liquid fuel from migrating along the venting path to the external environment. However, under conditions such as where an excessive amount of vibration is encountered in the operation of the machine carrying the fuel tank, the above-described fuel cap construction sometimes fails to prevent splashing of liquid fuel upward into the vent cavity and leakage thereof past the foam block through the venting path to the external environment.
A number of other fuel cap designs are known in the prior patent art. Representative of the prior art are the fuel caps disclosed in U.S. Pat. Nos. 3,961,724 4,168,012; 4,512,499 and 4,696,409. However, none of these other prior fuel caps appear to provide a satisfactory solution to the above-described problem. Consequently, a need exists for improvements which will overcome this problem without introducing a set of new ones in their place.